Reservoirs, a major component of California’s water storage system, are a significant source of climate-warming emissions, releasing more greenhouse gases across the state than 300,000 gas-powered cars in a year, says a report by the Center for Biological Diversity.
“Beneath the Surface” https://www.biologicaldiversity.org/programs/urban/pdfs/Beneath-the-Surface-Reservoirs-Report-Nov-2024.pdf?_gl=1*1ti4eyp*_gcl_au*Mzk5Njc4NzkyLjE3MjkwMjYxNTc outlines what the group says are the environmental threats of “big water infrastructure projects and why reservoirs’ water storage benefits will only diminish as climate change intensifies.”
The report comes as California plans three large reservoirs and dam expansion projects, including Sites Reservoir, that will cost a total of $7 billion.
The report says, “These and similar projects across the western U.S. would divert large quantities of water from nearby rivers and cause irreparable harm to imperiled fish and other wildlife.”
“Building new, expensive reservoirs won’t solve California’s water supply problems but will actually make things worse,” said Sofia Prado-Irwin, a staff scientist at the Center and lead author of the report. “As temperatures rise, these boondoggle projects will become less effective and they’ll emit massive amounts of polluting gases, making it harder to reach our climate goals. It’s time to move away from these outdated ideas and focus on floodplain restoration, water recycling and other climate-resilient measures that can truly secure our water supply for future generations.”
Reservoirs are often viewed as carbon neutral but recent studies have shed more light on their environmental harms. From construction to decommission, reservoirs emit methane and carbon dioxide for decades, says the report.
“When reservoirs are filled with water, the plants in the flooded area decompose, releasing harmful climate-warming emissions. While the reservoir is in operation, microbes in the sediment continue to release greenhouse gases, resulting in steady and ongoing emissions,” says the report.
“Water infrastructure projects that alter the flows of rivers and streams also have cascading effects on ecosystems, destroying habitat and disrupting wildlife connectivity.”
The report suggests climate-resilient solutions like creating permeable “sponge cities” that capture stormwater and nature-based flood management strategies to recharge groundwater.
“These solutions, when combined with water conservation, can help California meet its fluctuating water needs while still protecting ecosystem health,” says the report.